Shooting Sports USA - August 2018 - 30

FEATURE | VISION

Exam using pistol sights only: I need to
have the eyes relaxed as much as possible to
determine the best possible shooting Rx. I prefer using actual pistol iron sights to get good
patient feedback rather than an exam reading
card. In my office, the shooting patient can look
across the street and we use a round light fixture on the building as a bullseye target. Every
shooter will be able to identify his/her best lens
for their preferred sight picture. Quoting Philip
Hemphill, "My eye doctor here in Mississippi
gets a little uneasy when I bring my guns into
his office for sight picture correction, but I have
found that is the only way I can get a correct
adjustment for vision. The lighting also affects
the way I perceive the sights in his office."

BINOCULARLAR VS. MONOCULAR
TESTING AND THE TRIAD
Typically when we check eyes at near distances
in the confined space of the exam room, we
have both eyes opened with binocular testing. We then have what is known as the triad.
When one looks close up, the eyes must converge so that each eye will aim at the distance
of the reading card. With convergence, the
eyes also accommodate and the pupil size become smaller. In accommodation, the muscles
inside the eye changes causing the shape of
the lens to change and thereby the focus. Even
older shooters who wear multifocal lenses
can still accommodate to a certain degree. For
instance, a 60 year old shooter can accommodate 1.00 diopter. We also know that changes in
pupil size can change the way we see.
These factors may affect our shooting prescription when doing near binocular testing
while using a reading card. I've heard a number of times from shooters that even though
the eye doctor used the measurement of the

30

AUGUST 2018 | SSUSA.ORG

Jim O'Young, 2016 Steel Challenge Senior Division
Winner, here wearing his corrective lenses

eye to the front sight, the shooting Rx was
off. While doing monocular testing with iron
sights, the triad would no longer be a factor
and a more consistent outcome will result.
Depth of field: I simulate the lighting
conditions as close as possible to the shooting
environment. When one needs to see outdoors
to compete in daylight, we have large windows
to allow plenty of light to the shooter's eyes,
which will have a positive effect onto the pupil
by making it smaller. With smaller pupils, we
have an extended depth of field. At this point,
the smaller pupil become advantageous for
the sight picture. This topic is further discussed
in a previous article.
When we look at the front sight, the bullseye
will be blurred, but how much blur is preferable
if the front sight is clear? We can have 20/25
blur or 20/100 or more blur. A very blurred
bullseye at 50 yards may make it difficult to
judge the sight picture and be frustrating. By
checking the shooter's vision while looking at
the front sight in relationship to the rear sight
and then the bullseye, the shooter will be able
to "decide" on their lens preference without the


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Table of Contents for the Digital Edition of Shooting Sports USA - August 2018

Contents
Shooting Sports USA - August 2018 - Cover1
Shooting Sports USA - August 2018 - Cover2
Shooting Sports USA - August 2018 - 3
Shooting Sports USA - August 2018 - 4
Shooting Sports USA - August 2018 - 5
Shooting Sports USA - August 2018 - Contents
Shooting Sports USA - August 2018 - 7
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